New Front Discs/Pads Problem

Samuelle · 24th June 2011, 10:28

Hello Again Forum

I fitted new front discs/pads last night, and everything seemed to go smoothly for a change - no seized threads, missing tools etc. This all felt too good to be true

. I gave it a drive this morning, and there is bad pulsing through the brake pedal. You can feel the peddle going up and down with each rotation of the wheel. It's bucketing it down with rain here atm, so I haven't looked for any obvious warping, but I just wanted to check in here first that there isn't some nube mistake I could have made.

I didn't go the (what looked like) overcomplicated Haynes manual route of fully dismantling the calliper to fit the pads, I just put the new pads in the still assembled calliper while it was off the disc, and pushed the excess fluid back up through the system rather than out the calliper bleed nipple. I cleaned up the surface of the stub axle where the disc is mounted. The parts are a cheap mintex set from Pro-Parts Peterborough on Ebay. So.. duff disc? or could I have done something stupid here?

kissifer1972 · 24th June 2011, 11:22

Did you clean the discs with brake cleaner prior to fitting?

They have oily coating to stop them rusting. Could just be that the pads are not quite gripping the surface of the disk properly.

Must admit I always disassemble the carrier from the caliper and give everything a really good clean with a wire brush before I put the new pads in.

If a disc is warped, which mine was and why I recently fitted new Mintex pads and discs to the from of mine, you can feel it through the steering too.

You can get a faulty disc, but I have to say I never have.

Best thing to do would be to strip it all down again. Clean it all up and re-assemble and see if the problem is still there.

Chris

carlpenn · 24th June 2011, 11:35

I agree with Kissifer1972 / Chris.

I stripped mine right down and cleaned the surfaces, then applied Coppergrease to any surface that contacted each other as well as the Pad backs - But obviously not the actual brake pad / disc contacting surface

.

Also, I don't know if it ever has happened to anyone, but when you push the piston back it apparently risks "Flipping" a one way valve in the system, so I would recommend clamping off the Brake hose and opening the Bleed nipple to do this. Better safe than sorry as it can apparently cause total brake loss.

chris75 · 24th June 2011, 11:52

Quote:

Originally Posted by kissifer1972

Did you clean the discs with brake cleaner prior to fitting?

They have oily coating to stop them rusting. Could just be that the pads are not quite gripping the surface of the disk properly.

Best thing to do would be to strip it all down again. Clean it all up and re-assemble and see if the problem is still there.

Chris

Agreed as well

Strip it down and redo it !
Make sure nothing is trapped between the disc flat and the hub carrier , and that the little set screw is fully home . I have myself never had any bother when gently pushing the pistons back ; I think it is the rubber seal that people worry about flipping , but I have never heard of anyone it happened to

damienp · 24th June 2011, 12:06

Jack one front wheel up off the ground. Start the car up and go through the first couple of gears. Stamp on the brakes when you get into 3rd (remembering not to stall it). If the braking does the same then the spinning wheel is the guilty one. I would then put your old disc and pads back on and repeat the process. If your braking is then smooth, then i would assume you have a warped disc.

spyder · 24th June 2011, 12:57

Check that you did not disturb the ABS, make sure the dash ligh is working as it should. The abs will give you a similar pulse when it is activating. Dont know how it would affect in this case, but rather check it out.

Craig

Samuelle · 24th June 2011, 13:00

Quote:

Originally Posted by chris75

Agreed as well

Strip it down and redo it !
Make sure nothing is trapped between the disc flat and the hub carrier , and that the little set screw is fully home . I have myself never had any bother when gently pushing the pistons back ; I think it is the rubber seal that people worry about flipping , but I have never heard of anyone it happened to

Thanks for the advice guys. I'll have another look if it ever stops raining. I'm pretty much sure I cleaned up the carrier and mounted the disc ok, and I took is slow when I pushed the piston in with a g-clamp centred on it

. My money is on a faulty part, but I hope I have to eat my words when I find I've somehow mounted the disc badly. A faulty mail order disc is a right pita.

Samuelle · 24th June 2011, 13:11

Quote:

Originally Posted by damienp

Jack one front wheel up off the ground. Start the car up and go through the first couple of gears. Stamp on the brakes when you get into 3rd (remembering not to stall it). If the braking does the same then the spinning wheel is the guilty one. I would then put your old disc and pads back on and repeat the process. If your braking is then smooth, then i would assume you have a warped disc.

At first I thought you were joking, but I presume you mean doing this with the clutch engaged

Sounds like a good idea.

Quote:

Originally Posted by spyder

Check that you did not disturb the ABS, make sure the dash ligh is working as it should. The abs will give you a similar pulse when it is activating. Dont know how it would affect in this case, but rather check it out.

Craig

I'm not even sure if I have ABS. Is it standard on all cdti's? I'll have a look. Could that have been damaged when I pushed the fluid back through the system?

James.uk · 24th June 2011, 13:12

I had two new front disks fitted not long ago, and it turned out they were BOTH faulty and had to get them replaced under their guarantee..

...

spyder · 24th June 2011, 13:25

I'm not even sure if I have ABS. Is it standard on all cdti's? I'll have a look. Could that have been damaged when I pushed the fluid back through the system?

An ABS light will/does show up on the dash when the ignition is turned on.
I have pushed the piston back on many cars and never had a problem. An interesting question though, as the oil is pushed back through the abs pump?? Maybe someone that knows a lot about the abs system can answer that.
I have a back gorund in hydraulics (that why I can spell it), and pushing the seal back needs to be done very fast and skew, befor it will damage or pop the seal.

Craig

24th June 2011, 10:28	#1
Samuelle Regular poster MG ZT CDTI 135+ Join Date: Jul 2008 Location: Sussex Posts: 84 Thanks: 8 Thanked 0 Times in 0 Posts	New Front Discs/Pads Problem Hello Again Forum I fitted new front discs/pads last night, and everything seemed to go smoothly for a change - no seized threads, missing tools etc. This all felt too good to be true. I gave it a drive this morning, and there is bad pulsing through the brake pedal. You can feel the peddle going up and down with each rotation of the wheel. It's bucketing it down with rain here atm, so I haven't looked for any obvious warping, but I just wanted to check in here first that there isn't some nube mistake I could have made. I didn't go the (what looked like) overcomplicated Haynes manual route of fully dismantling the calliper to fit the pads, I just put the new pads in the still assembled calliper while it was off the disc, and pushed the excess fluid back up through the system rather than out the calliper bleed nipple. I cleaned up the surface of the stub axle where the disc is mounted. The parts are a cheap mintex set from Pro-Parts Peterborough on Ebay. So.. duff disc? or could I have done something stupid here?

24th June 2011, 11:22	#2
kissifer1972 Posted a thing or two Rover 75 CDTi Conn Tourer & Rover 75 CDT Conn SE Saloon Join Date: May 2010 Location: Queensbury Posts: 1,368 Thanks: 0 Thanked 1 Time in 1 Post	Did you clean the discs with brake cleaner prior to fitting? They have oily coating to stop them rusting. Could just be that the pads are not quite gripping the surface of the disk properly. Must admit I always disassemble the carrier from the caliper and give everything a really good clean with a wire brush before I put the new pads in. If a disc is warped, which mine was and why I recently fitted new Mintex pads and discs to the from of mine, you can feel it through the steering too. You can get a faulty disc, but I have to say I never have. Best thing to do would be to strip it all down again. Clean it all up and re-assemble and see if the problem is still there. Chris __________________ Mods so far X-Power Performance Upgrade LED interior lights and sidelights Genuine Rover Xenons - now removed and sold Kenlowe fan Synergy 2 EGR Bypass

24th June 2011, 11:35	#3
carlpenn This is my second home 2000 Wedgey Blue 2.5V6 Beauty Join Date: Jul 2007 Location: Bilston Posts: 4,486 Thanks: 36 Thanked 29 Times in 16 Posts	I agree with Kissifer1972 / Chris. I stripped mine right down and cleaned the surfaces, then applied Coppergrease to any surface that contacted each other as well as the Pad backs - But obviously not the actual brake pad / disc contacting surface . Also, I don't know if it ever has happened to anyone, but when you push the piston back it apparently risks "Flipping" a one way valve in the system, so I would recommend clamping off the Brake hose and opening the Bleed nipple to do this. Better safe than sorry as it can apparently cause total brake loss. __________________ 2.5V6 Auto: Work carried out so far: Crankcase Breather Pipe replaced, O/S CV Joint replaced, Starter Motor Repair Kit Fitted, Front Suspension Overhauled.

24th June 2011, 12:57	#6
spyder This is my second home 75 CDT Auto Tourer , Rover 45 , Astra, Zaffira, Chev Captiva Join Date: Mar 2011 Location: Wilts Posts: 3,342 Thanks: 203 Thanked 436 Times in 360 Posts	Check that you did not disturb the ABS, make sure the dash ligh is working as it should. The abs will give you a similar pulse when it is activating. Dont know how it would affect in this case, but rather check it out. Craig __________________ Chrome skull caps, EGR cleaned (original housing), Mondeo lower mounting, 12V outlets in the armrest and tourer boot, cat fixed, working FBH, Lidl plenum covers, DD with reverse camera.New speakesr/Tweeters with MDF rings. wood dash, Memory leather seats, wooden finished steering and handbrake, Xenon headlights.

24th June 2011, 13:25	#10
spyder This is my second home 75 CDT Auto Tourer , Rover 45 , Astra, Zaffira, Chev Captiva Join Date: Mar 2011 Location: Wilts Posts: 3,342 Thanks: 203 Thanked 436 Times in 360 Posts	I'm not even sure if I have ABS. Is it standard on all cdti's? I'll have a look. Could that have been damaged when I pushed the fluid back through the system? An ABS light will/does show up on the dash when the ignition is turned on. I have pushed the piston back on many cars and never had a problem. An interesting question though, as the oil is pushed back through the abs pump?? Maybe someone that knows a lot about the abs system can answer that. I have a back gorund in hydraulics (that why I can spell it), and pushing the seal back needs to be done very fast and skew, befor it will damage or pop the seal. Craig __________________ Chrome skull caps, EGR cleaned (original housing), Mondeo lower mounting, 12V outlets in the armrest and tourer boot, cat fixed, working FBH, Lidl plenum covers, DD with reverse camera.New speakesr/Tweeters with MDF rings. wood dash, Memory leather seats, wooden finished steering and handbrake, Xenon headlights.

24th June 2011, 12:06	#5
damienp This is my second home skoda estate Join Date: Feb 2009 Location: sheffield Posts: 3,474 Thanks: 15 Thanked 122 Times in 68 Posts	Jack one front wheel up off the ground. Start the car up and go through the first couple of gears. Stamp on the brakes when you get into 3rd (remembering not to stall it). If the braking does the same then the spinning wheel is the guilty one. I would then put your old disc and pads back on and repeat the process. If your braking is then smooth, then i would assume you have a warped disc.

24th June 2011, 13:12	#9
James.uk Passed Away 2002 Pale Blue. Rover 75 CDTi Connoisseur auto. 170K miles Join Date: Dec 2008 Location: Near the M67. Posts: 14,509 Thanks: 199 Thanked 585 Times in 397 Posts	I had two new front disks fitted not long ago, and it turned out they were BOTH faulty and had to get them replaced under their guarantee.. ...